Deformation Behavior of Al-Mg/B_4C and Al-Mg/TiC Composites Fabricated by Pressureless Infiltration Technique

摘要

Deformation behaviors of Al-Mg/B_4C and Al-Mg/TiC composites fabricated by pressureless infiltration technique were studied in the temperature range between 298K and 773K. The strength decreased similarly for Al-Mg/B_4C and Al-Mg/TiC composites, but the ductility of Al-Mg/B_4C was higher and reached to 150% at 773K. The stress exponents and the activation energy for high temperature deformation were observed to be 7 approx 8 and 180 approx 220KJ/mole respectively. The relatively high stress exponent and high activation energy can be explained in terms of dynamic solution-dislocation interaction in the matrix of Al-Mg composites. The activation volume for high temperature deformation of Al-Mg matrix composites increased from 50 approx 80b~3 at 573 K to 200 approx 800b~3 at 773 K. the rate controlling mechanism of the deformation for Al-Mg matrix composites was well explained by the dislocation trough model in which the segregation of alloying elements on dislocation determines the activation length.